Assign a shortcut to "Limit selection to visible" toggle
This is not available by default in preferences but you can add it manually. Open your user preferences and go to the Input tab, toggle 3D View and then Mesh.



Scroll to the bottom where you will see a button that says Add new. For the identifier, enter wm.context_toggle and for the Context Attributes enter space_data.use_occlude_geometry, next assign a key combination to it and save your user settings.